Retrievable plug



Sept. 12, 1961 H. L.. BIGELOW RETRIEVABLE PLUG Filed June 3, 1957 my W 1SWE INVENTOR, Hfe'r L. /afmn/ fram/yr lower inner sleeve valve. `intact,upper and lower side seals 18 on the sleeve valve United States, Parser2,999,545 REVABLE PLUG Herbert L. Bigelow, Whittier, Calif., assgnor toBaker Oil Tools, Inc., Los Angeles, Calif., a corporation of CaliforniaFiled .lune 3, 1957, Ser. No. 663,288 7 Claims. (Cl. 166-153) Thepresent invention relates to subsurface well bore devices, and moreparticularly to a subsurface device useful in the perfomance ofcementing and similar operations in well bores.

An object of the present invention is to provide a plug for closing thepassage in a well conduit aganist downward flow of fluid therethrough,which plug is readily retrievable from the well casing when desired,despite the resisting force of a substantial hydrostatic head of uidthereabove. Another object of the invention is to provide a plug forclosing the central passage through a sleeve valve that Icontrols theflow of fluid through side ports in a well bore conduit, the plug beingreadily retrievable whenever reopening ot the central passage isrequired.

This invention possesses many other advantages and has other objectswhich may be made more clearly apparent from a consideration of a formin which it may `be embodied. This form is shown in the drawings ac-FIG. 2 is a longitudinal section, with parts shown in elevation, of theplug disclosed in FIG. l in a condition 'to be retrieved from the wellcasing and to be'withdrawn to the top of the well bore.

The retrievable plug A illustrated in the drawings is shown by way ofexample in conjunction with a stage cementing collar B which is securedto upper and lower casing sections C, D. Such cementing collars are usedto enable cement to be discharged from a lower point in the string ofwell casing disposed in a well bore, the collar being in a closedcondition. Thereafter, the collar is opened in order to establishcirculation therethrough, and another stage of cementing is performed bydischarging the cement from the casing outwardly through openings in thestage collar for upward passage around the casing string.

As illustrated in the drawings, the stage collar B is of the specic typeshown and described in United States Patent 2,655,216. It is to beunderstood, however, that the invention is useful in conjunction withother specific apparatus than the one disclosed. This stage coliar Bincludes a main tubular member 10 having an upper threaded box 11threadedly secured to the lower pin end 12 of the upper casing sectionC, and a lower threaded 'pin 13 threadedly secured to the upper boxportion 14 of the lower casing section D. The tubular member 10 has aplurality of side ports 21 extending therethrough,

initially closed by a lower inner sleeve valve 16 held in Lthe closedcondition by one or more shear screws 17 threaded through the tubularmember lt) and into the When the shear screws 17 are vare located onopposite sides of the ports 15.

After they have been placed in open condition, as described hereinbelow,the side ports 21 can be reclosed l Ce by an external sleeve valve 19slidable along the exterior of the tubular member 10, this sleeve valvebeing disL posed initially in a port opening position by shear screws 20extending therethrough and into the tubular member. When the shearscrews 20 are intact, side ports 15 extending through the externalsleeve valve are aligned with the side ports 21 of the tubular member10. At this time, lower and intermediate side seal rings 22, 23 mountedon the external sleeve valve 19 are disposed on opposite sides of thetubular member ports 21, sealing against the periphery of the tubularmember.

The sleeve valve 19 is shifted downwardly when the shear screws Ztl aredisrupted to close the tubular member ports 21, the extent of downwardmovement being limited by engagement of the lower end 24 of the externalsleeve valve with a stop sleeve 25 suitably secured to the tubularmember 10, as by means of the screws 25. When engaged with this stopsleeve 25, the external sleeve valve member 19 has closed the tubularmember side ports 21, leakage between the external sleeve valve memberand the tubular member 10 then being prevented by intermediate and upperseal rings 23, 27 on the external sleeve valve member disposed insealing engagement against the tubular member on opposite sides of theside ports 21.

The external sleeve valve member 19 has an intermediate inner shoulder23 from which anupper portion 29 of the sleeve valve slidably extendsalong a side sal ring 3G mounted on the tubular member 1t); The shearscrews Ztl are disrupted and the external sleeve valve member 19 shifteddownwardly to a port closing position whenever an upper inner sleevevalve member 31l is shifted downwardly in the tubular member. This upperinner sleeve valve member 31 is initially disposed across longitudinalslots 32 extending through the tubular member, being held in thiscondition by shear screws 33` attaching it to the tubular member 1d.Keys 34- extend through the slots 32 and are secured to the inner sleevevalve member 31. When the inner sleeve valve member keys 34 are shifteddownwardly along the tubular member 10, they will engage the internalshoulder 28 on the external sleeve valve member 19. When suicient forceis imposed on the inner sleeve valve member 31, the screws 33 will bedisrupted, the inner sleeve valve member 31 moving downwardly to bringthe keys 34 into engagement with the shoulder 28 and then disrupting thescrews 20 to shift the external sleeve valve member 19 down to its portclosing position in engagement with the stop sleeve 25. When thiscondition obtains, an inherently expansible latch ring 35, mounted in anexternal groove 36 in the tubular member lil, will have its upperportion 37 spring out across the upper end of the external sleeve valve19 to hold the latter in its lower port closing position.

The several positions of the inner and outer sleeve valve members 16,31, 19 are not illustrated in the present case since they areunnecessary to Ian understanding of the present invention and may befound in the aboveidentified patent. It is sufficient to state that thetrip plug A moves down the casing string whenever the ports 21 and 15are -to be opened, seating upon the lower inner sleeve valve 16,whereupon iluid pressure may be imposed on the plug to overcome theforces of shear screws 17 and thereby shift the lower sleeve valve 16downwardly below the ports 15 to the extent determined by engagement `ofits lower portion with a stop ring 38 attached to the tubular member.When in this position, the side ports 15 are opened and circulatingfluid can then be pumped down through the casing string and the openports 15, 21 for upward passage around the exterior of the casing towardthe top of the well bore.

After the desired operation has been performed with the ports 2.1 and 15open, such as a cementing operation,

a top cernenting or shut-ofi plug (not shown) will engage the upperysleeve valve 31. Pressure imposed on the fluid above such plug will beexerted downwardly on the upper inner sleeve valve 31 to` disrupt thescrews 33, shifting its keys 34 down into engagement with the externalsleeve valve shoulder 28, overcoming the shearstrength of the screws to`disrupt the latter, and then shifting the externjal sleeve valve 19down to its port closing position, the latch ring 35 then engaging theupper end of the external sleeve valve 19 to prevent its return orupward movement to aport opening position.

Under some conditions, it is desirable to retrieve the trip plug A,which is herein illustrated as closing the central passage through thelower inner sleeve valve 16 after it 4has been shifted downwardly toopen the side ports 21 and 15. As an example, it may be desirable toopen Isuch side ports 21 to establish circulation around Vthe casingland then run a temperature surveying instrument through the stagecollar B to ascertain the location of the lower cementing job, such asthe charge of cement slurry that had previously been pumped down throughthe casing for discharge from a shoe (not shown) or other point in thecasing string below the ported collar B. Quite obviously, the presenceof the trip plug A would prevent the temperature survey from beingtaken. Accordingly, the present tripy plug is of the retrievable typeand can be withdrawn from the well casing after the side ports 21 and 15through the collar have been opened.

As disclosed, the trip plug A includes a lower body 50 having a taperedguide 51 and circumferentially spaced longitudinally extending`centering ribs or wings 52, the upper and lower ends 53, 54 of thewings also being tapered to prevent the plug lfrom hanging up on sharpedges and the like inthe casing string, during longitudinal 'movement ofthe plug therewithin. The upper tapered portion 53 of the body 50 mergesinto a tubular neck portion 55, which, inturn, merges into a plug orvalve head 56, the bottom portion 57 of which diverges in an upward andoutward direction. This head ha a circumferential groove 58 to receive asuitable seal ring 59, such as a lip type of rubber or rubber-likeannular sealing member, adapted to engage a circumferential seat 60 inthe upper portion of the lower inner sleeve valve 16.

The tubular neck 55 and head 56 have a communicating passage 61 whichcan be closed by a plug 62 disposed in the upper portion of the passageand releasably held therein by one or more shear screws 63 extendingthrough a transverse hole 64 in the head and threaded into the plug 62.Leakage around the exterior of the plug is prevented by a suitablesealing ring 65, such as a rubber or' rubber-like 0 ring, mounted in aring groove 66 in the -plug and engaging the cylindrical wall 67 of thepassage. The upper portion 68 of the plug is reduced in diameter so thatuiid above the plug can be displaced around the plug upon disruption ofthe shear screw 63, in a manner and under the conditions describedhereinbelow.

The plug 62 within the head 56 has a central passage 69 therethrough,the lower portion 7i) of which is of a much smaller diameter than itsupper portion 71, The upper portion 71 actually constitutes acylindrical valve seat within which an upper valve head 72 may bedisposed. This valve head has a peripheral groove 73 ltherein on whichis mounted a side seal 74, such as a rubber or rubber-like O ring,adapted to sealingly engage the cylindrical valve seat 71 when the lowerend 75 of the. head engages an inner stop shoulder 76 in the plug, asillustrated in FIG. l. Depending from the head 72 is a stem 77 which maybe integral therewith, this stem extending through the smaller diameterplug passage 76 and having a substantially smaller diameter than l-theinternal diameter of this passage. Surrounding the lower portion of thestem is a helical compression spring 78,-the upper end of which bearsagainst the lower end of the lplug 62 and the lower end of which bearsagainst a spring seat in the form of a washer 79 prevented from'shifting 'downwardly on the stem by a'nut 86"'threaded on the lower endof the stem. The spring 78 normally urges the stem 77 and valve head 72in a downward direction with respect to the plug 62, to hold the head 72and its seal ring 74 within the valve seat 71, thereby closing thecentralpassage 69 through the plug against downward owof the uidtherethrough.

The head 72 has an upper extension 81 provided with a hole 82therethrough into which the lower end of a wire line E can be threaded,the end of the wire line then being suitably secured to'the portion ofthe wire line thereabove, so .as to connect the wire line E to the valvemember 72. This wire line will extend to the top of the well bore andaround suitable winding or reeling equipment (not shown) The neck 55 ofthe trip plug has a side port 85 providing communication between thepassage below the plug 62 and exterior of the plug, in order topermitfluid to ilow between the passage and lthe exterior of the plugunder certain conditions that will he described hereinbelow.

To facilitate the retrieval of the plug A from the well casing and toprevent its hanging up on restrictions `and the like, an adapter orextension 86 is secured to ythe plug head 56, as by means of the capscrews 87. This adapter or extension has a central passage 88 coincidingwith the passage 61 through the head, the upper outer portion 89 of theadapter being beveled or tapered in an upward and inward direction so asto guide `the trip plug safely past coupling spaces and similar abruptportions in the casing string. The upper surface 90 of the adapter isfrusto conical in shape, providing a guide or tapered surface for a ballor similar element (not shown) which may be used in conjunction with theapparatus.

The lower body 50, neck 55, head S6, plug 62 and adapter 86 may beconsidered as constituting a valve device having a passage 88, 69, 61,therethrough. The plug 62 of the valve device has the valve seat 71therein, which surrounds the portion 69 of the passage.

In using the apparatus, the collar B is suitably secured to the upperand lower casing sections C, D and the casing string is lowered in thewell bore to the desired depth. At this time, the collar parts are inthe position illustrated in FIG. l, in which the lower inner sleevevalve 16 VVis disposed across the ports 15 to close the same. A lowerstage cementing operation can be performed by pumping .the proper chargeof cement slurry down the casing string and through the collar B fordischarge from the casing at some point below the collar. Thereafter, itis desired to open the side ports 21 and 15. The trip plug A is secured`to the lower end of the wire line E and is then allowed to gravitatethrough the fluid in the well casing, this plug coming to rest on theinner sleeve valve 16 with the seal ring 59 engaging the seat 60 at theupper portion of this sleeve valve. The central passage through thelower sleeve valve 16 is now closed, which permits uid pressure abovethe trip plug to be increased to the point at which the shear strengthof the screws 17 is exceeded, these screws being disrupted `and thelower plug A and lower inner sleeve valve 16 then being forceddownwardly to the extent determined by engagement of the .sleeve valvev16 with the top ring 38. At this time, the tubular member ports 21 willbe open, and circulation of uid can be established through such openports, the fluid being pumped down the casing and out through Vthe ports21V and 15, then owing upwardly around the exterior of the casing.

After the circulation has been established, it is desired to retrievethe trip plug A. This is done by elevating Vthe line E. However, it isoftentimes diicult to raise the plug from the collar B because of thehydrostatic head of fluid thereabove. It would be necessary to overcomethe force of such iluid over substantially the entire area of the plugA. In the present instance, the pressure both above and belowthe plug isequalized by taking an upwardpuu n .the 'wireline E] 'whaha' win pun thevalvel head 72 upwardly of the plug 62 and the trip plug head1' 56against the force of the spring 78, raising the sealring 74 above thecylindrical valve seat 71. The force required to shift the head 7.2upwardly is relatively small; in view of the apparently smallcross-sectional area of the head. Once the seal ring 74 has beenelevated above the cylindrical seat 71, the region above the plug A isplaced in communication with the region below its side seal ring 59through the intercommunicating passages 88,` 69, 70 in the adapter 86and the plug 62, the `passage 61 below the plug 62, and the side port 85through the' trip plug neck 55. The plug A can now be elevated by thewire line vE from the valve seat 60 and withdrawn completely from thewell casing without difliculty. During such elevating movement, thebeveled edge vor guide portion 89 on the adapter 86 will prevent theplug A from hanging up or catching on portions of the Well casing, ,Asuch als the lower ends of casing sections at Vthe points where thesectionsV are coupled to one another.

l Following the removal of the trip plug A from the well casing, atemperature survey can be run of the bottom cementing job by loweringthe necessary equipment through the casing string and through the collarsleeves 31, 16 to the desired point therebelow. When the surveyinginstruments havebeen withdrawn, it may be desired to perform thecementing job through the open ports 21 and 15. At this time the tripplug A detached from the wire line E can be dropped into the wellcasing, and will gravitate to its companion seat 60 on the lower innersleeve valve 16. Circulation can now be established by pumping fluiddown the casing string and through the open ports 15, 21 for upwardpassage around the well casing. The required quantity of cement slurrycan also be pumped into the casing string and discharged through theopen ports, this cement slurry having the usual top cementing plugthereon which will engage a companion seat 95 on the upper, inner sleevevalve 31, shearing the screws 33 and shifting the valve 31 downwardly todisrupt the shear screws 20 and shift the external sleeve valve 19 downalong the tubular member to a position fully closing the ports 15, withthe side seals 23, 27 on opposite sides of such ports, to preventleakage through the collar B.

At times during the downward shifting of the top cementing plug and theupper inner sleeve valve 31 to shift the external valve 19 to portclosing position, fluid may be trapped between such upper plug and thetrip plug A, particularly in the event the external sleeve Valve hasshifted across the side ports to close the same. The presence of suchentrapped fluid can be allowed to bypass through the lower trip plug A.When the pressure imposed on such fluid exceeds the shear strength ofthe screws 63 holding the inner plug member 62 to the trip plug head 56,the screw will be disrupted and the entire valve assembly 72, 77, 78 andtrip plug 62 shifted downwardly to a position in which the lower portionof the trip plug 62 and its seal ring 65 are disposed below the upperend of the side port 85 through the plug neck. The fluid trapped betweenthe upper and lower cementing plugs can now pass downwardly through thecentral passages 88, 61 through the trip plug, around the upper portion68 of plug 62, and then out through the port 85.

The shear screw 63 holding the plug 62 to the head 56 is usuallyselected to shear at a comparatively high unit pressure, so that theunit pressure required is well above the shear value of the screws 17holding the lower inner sleeve valve 16 to the tubular member 10. Suchhigher pressure is desire since the passage 88, 61 through the trip plugA should normally be maintained closed, to insure the shearing of thescrews 17 holding the inner sleeve valve to the tubular member 10 andits downward movement to a port opening position. It is only whenentrapped uid conditions are encountered that the shear screw 63 isdisrupted to permit such trapped uid to pass throughl'the' tripplugAintothe "collar- B' and the casingD therebelow.` "The inventor claims:v1

`1. In a plug adapted for longitudinal movement ina well condui't "avalve device having a sealing surface adapted to vengage a companionseat in the well conduit; said device having a'passage through which uidmay ow between regions externally of said device above and below saidsealing surface; said device having a valve seat therein surroundingsaid passage; a valve member movable downwardly into engagement withsaid seat; said valve member having means connectible to a wire line tobe elevated by saidwire line from said seat to open said'passage; andmeans interconnecting said device and valve member with said valvemember elevated from said seat, whereby said device and valve member aremovable together upwardly in the well conduit.

2. In a plug adapted for longitudinal movement in a well conduit: avalve device having a sealing surface adapted to engage a companion seatin the well conduit; said device having a passage through which fluidmay flow between regions externally of said device above and below saidsealing surface; said device having a valve seat therein surroundingsaid passage; a valve member; spring means engaging said device andvalve member to urge the valve member downwardly into engagement withsaid seat; said valve member having means connectible to a wire line tobe elevated by said wire line from said seat to open said passage and tomove said device and valve member together upwardly in the well conduit.

3. In a plug adapted for longitudinal movement in a well conduit: avalve device having a sealing surface adapted to engage a companion seatin the well conduit; said device having a passage through which fluidmay ow between regions externally of said device above and below saidsealing surface; said device having a valve seat therein surroundingsaid passage; a valve member having a depending stem; spring meansengaging said stem and valve device to urge said valve member downwardlyinto engagement with said seat; said valve member having meansconnectible to a wire line to be elevated by said wire line from saidseat to open said passage and to move said device and valve membertogether upwardly in the well conduit.

4. In a plug adapted for longitudinal movement in a well conduit: afirst valve member having a sealing surface adapted to engage acompanion seat in the well conduit; said member having a first passagethrough which fluid may flow between regions externally of said memberabove and below said sealing surface; a tubular member in said irstpassage sealingly engaging said first member, said tubular member havinga second passage therethrough communicating with said first passage;means releasably securing said tubular member in said first memberpassage; said tubular member having a valve seat surrounding said secondpassage; and a second valve member movable downwardly into engagementwith said seat; said second valve member having means connectible to awire line to be elevated by said Wire line from said seat to open saidsecond passage.

5. In a plug adapted for longitudinal movement in a well conduit: afirst valve member having a sealing surface adapted to engage acompanion seat in the Well conduit; said member having a first passagethrough which uid may ow between regions externally of said member aboveand below said sealing surface; a tubular member in said first passagesealingly engaging said first member, said tubular member having asecond passage therethrough communicating with said first passage; meanslreleasably securing said tubular member in said rst member passage;said tubular member having a valve seat surrounding said second passage;a second valve member movable downwardly into engagement with said seat;said second valve member having means connectible to a wire line to beelevated by said wire line from said seat to open said second passage;and means interconnecting said second valve member and tubular member,whereby said valve members and tubular member are movable togetherupwardly `in the well conduit.

6. In a plug adapted for longitudinal movement in a w'ell conduit: afirst valve member having a sealing surface :adapted to engage acompanion seat in the well conduit; said member having a iirst passagethrough which uid may ilow between regions externally of said memberabove and below said sealing surface; a tubular member in said iirstpassage sealingly engaging said rst member, said tubular member having asecond passage therethrough communicating with said rst passage; meansreleasably securing said tubular member in said iirst member passage;said tubular member having a valve seat surrounding said second passage;a second valve member; spring means engaging said second valve memberand tubular member to urge said second valve member downwardly intoengagement with said seat; said second Valve member having meansconnectible to a wire line to be elevated by said wire line from saidseat to open said second passage and to move said valve members andtubular member together upwardly in the well conduit.

7. gIn a plug adapted for longitudinal movement in a well conduit: aiirst valve member having a sealing surface adapted to engage acompanion seat in the well conduit; said member having a rst passagethrough which nid may flow between regions externally of said memberabove and below said sealing surface; a tubular member in said Vfirstpassage sealingly engaging said first member, said tubular member havinga second passage therethrough communicating with said first passage;means Areleasably securing said tubular member in said first memberpassage; said tubular member having a valve seat surrounding said secondpassage; a second valve member having a depending stem extending throughsaid second passage; spring means engaging said stem and tubular memberto urge said second valve member downwardly into engagement with saidseat; said second Valve member having means connectible to a wire lineto be elevated by said wire line from said seat to open said secondpassage and to move said valve members and tubular member togetherupwardly in the well conduit.

References Cited in the file of` this patent UNITED STATES PATENTS

